Dear Zhenkun_yuan,
as far as I can see it these problems have been resolved in VASP 6.4.3 and newer after hearing the concerns of the community as fast as possible. I fear that not all consequences of updates / changes can be foreseen, but rest assured that backward compatibility is one of the cornerstones of VASP development. Hence, these things should happen only very rarely and we will try to fix them as fast as possible.
Best regards,
Alex H.